Association Between ILO Abnormalities and Exposures Among Former Nuclear Weapons WorkersMarek Mikulski1, Spencer Lourens2, Jacob Buhrow3, Jill Welch1, Valentina Clottey1, Nicholas Hoeger1, Christina Nichols1, Zheng Wang1, Patrick Hartley3, Nancy Sprince1, and Laurence Fuortes1

1Department of Occupational and Environmental Health, College of Public Health, University of Iowa, Iowa City, IA2Department of Biostatistics, College of Public Health, University of Iowa, Iowa City, IA

3Carver College of Medicine, University of Iowa, Iowa City

AB

Abstract

Iowa Army Ammunition Plant (IAAAP)

Exposure Categories/Jobs

Project Background

ResultsMethods

Summary of Findings/ConclusionsJob Exposure Matrix

Results

Nuclear weapons industry workers are recognized as being at risk for a

variety of work-related respiratory exposures which may be associated

with occupational lung disease. We reviewed CXRs of 757 former AEC

nuclear weapons workers from the Iowa Army Ammunition Plant (IAAAP)

in Burlington, IA screened for evidence of parenchymal and pleural

abnormalities consistent with pneumoconiosis according to the 1992

International Labour Organization (ILO) Classification of Radiographs of

Pneumoconioses. The screenings were part of the Department of Energy

(DoE) Former Worker Program established in 1996 to identify hazardous

exposures in atomic weapons production, and provide medical screenings

to detect health effects from those exposures.

We found 60 former DoE workers (7.9%) with parenchymal abnormalities

defined as ILO profusion score of 1/0 and greater. Of those, 42 (5.6%)

had only parenchymal abnormalities and 18 (2.4%) had accompanying

pleural abnormalities. In addition, 35 workers (4.6%) had isolated pleural

abnormalities consistent with pneumoconiosis. A suggested dose-

response trend was found between exposure to high explosives and

parenchymal abnormalities, and exposure to asbestos and

parenchymal/pleural and pleural abnormalities. The prevalence of

parenchymal abnormalities was comparable or higher than rates in other

DoE sites. These results confirm the need to screen former nuclear

weapons workers for effects of airborne exposures in the manufacture of

nuclear weapons.

The University of Iowa College of Public Health Project started in 2001

Funded by DoE under Public Law 102-484 Section 3162 of the 1993

Defense Authorization Act

Goal: Identifying, locating, and providing former IAAAP DoE workers

employed in the manufacture of nuclear weapons with medical evaluation

of long term health effects that might have resulted from employment

Located in Middletown, IA (Des Moines County) ~ 70 miles south from

Iowa City - over 19,000 acres of Government Owned Contractor Operated

(GOCO) establishment with >1000 buildings, 142 miles of roads and 103

miles of railroad tracks

Built between 1941-1943 as conventional munitions (DoD) Loading,

Assembly and Packing (LAP) facility. Atomic weapons assembled,

disassembled and repaired between 1949 and mid-1975 on Line 1 under

Atomic Energy Commission (AEC, pre-DoE) contractual agreements with

Silas-Mason Company

Production terminated/moved in 1975 to Pantex, Amarillo, TX

Estimated up to 7,000 workers worked on or were exposed to Line 1

operations (a.k.a. Division B) between early 1949 and mid-1975

Substantial cross-over of workforce with adjacent conventional munitions

manufacturing lines (95-100% of DoE workers worked on DoD lines too

during their tenure at the plant)

Still in operation - current workforce approx. 600 employees

Primary exposures:

- Ionizing radiation High Explosives incl. Barium

- Beryllium Isocyanates

- Asbestos Epoxy adhesives

- Solvents Curing agents

Cohort selection was based on subcontractor employment records, plant

radiation dosimetry records, union seniority records and employment

validation by other former workers.

Participants were recruited by mail, telephone, press releases, town hall

meetings and word of mouth.

All former workers participating in the screenings were offered CXR.

Postero-Anterior (PA) films were reviewed by 3 experienced ILO readers

blinded to radiologist’s reports and each other’s readings.

Average of 3 readings was used to reconcile inter-reader variability in ILO

profusion scoring.

Parenchymal abnormalities were defined as average ILO profusion score

>1/0. Pleural abnormalities were defined as those confirmed by at least 2

of 3 readers.

Beryllium, asbestos, high explosives and barium exposure categories for

each worker were assigned based on job codes/job titles in

subcontractor's and plant’s employment records.

Highest exposure ever for each worker was used to estimate personal

exposure

The only available historical exposure data – limited beryllium surface

wipe sample reports for 1970-1974 - served as indicators of the presence

and relative levels of beryllium on surfaces in various locations within the

plant - these could not be used to directly estimate workers’ inhalational

exposure to beryllium at the plant.

A survey of surface contamination at this facility in 2007 revealed only two

beryllium samples out of one hundred collected throughout the facility

which exceeded the DoE surface contamination housekeeping level of 3

µg/100 cm2 and both of these were from surfaces in the area in which

millwrights used belt sanders to occasionally resurface alloy tools.

(Sanderson et al., JOEH 5(7) p.475, 2008)

Interviews of former DoD and DoE workers - production, trade and health

and safety – were used to assess areas, activities and eras for risk of

beryllium, asbestos, and high explosives/barium exposure.

Job codes, job titles, and work tasks were reviewed by industrial

hygienists and a group of former workers to develop a qualitative exposure

matrix (JEM) for beryllium, asbestos, high explosives and barium. The

estimates for each job code/category were based on task frequency and

proximity to potential sources of airborne exposures and reflected the

group’s consensus.

Parameter Total screened N=704

n, (%)

Parenchymal (Y)

n, (%)

Parenchymal (N)

n , (%)

p-value

Gender

Male

Female

563 (80.0)

141 (20.0)

34 (6.0)

8 (5.7)

529 (94.0)

133 (94.3)

1.0a

Race

White

Other

674 (95.7)

30 (4.3)

41 (6.1)

1 (3.3)

633 (93.9)

29 (96.7)

1.0a

Age

< 59

60-69

70-79

80-89

> 90

117 (16.6)

217 (30.8)

260 (37.0)

103 (14.6)

7 (1.0)

2 (1.7)

8 (3.7)

19 (7.3)

12 (11.7)

1 (12.5)

115 (98.3)

209 (96.3)

241 (92.7)

91 (88.3)

6 (87.5)

0.0003b

Smoking

Ever-smoker

Never smoker

Missing

481 (68.3)

221 (31.4)

2 (0.3)

31 (6.4)

11 (5.0)

-

450 (93.6)

210 (95.0)

2 (100.0)

0.61a

First date of hire

1/1/1947-12/31/1950

1/1/1951-12/31/1953

1/1/1954-12/31/1964

1/1/1965-6/30/1975

Missing

82 (11.6)

179 (25.4)

133 (19.0)

300 (42.6)

10 (1.4)

12 (14.6)

11 (6.1)

11 (8.3)

7 (2.3)

1 (10.0)

78 (85.4)

179 (93.9)

129 (91.7)

302 (97.7)

9 (90.0)

0.0002b

Beryllium exposure

Cat 0

Cat 1

Cat 2

Cat 3

Missing

343 (48.7)

301 (42.7)

47 (6.7)

-

13 (1.9)

18 (5,3)

21 (7.0)

2 (4.3)

-

1 (7.7)

342 (94.7)

297 (93.0)

46 (95.7)

-

12 (92.3)

0.68b

High explosives exposure

Cat 0

Cat 1

Cat 2

Cat 3

Missing

240 (34.1)

144 (20.5)

51 (7.2)

256 (36.4)

13 (1.8)

13 (5.4)

5 (3.5)

3 (5.9)

20 (7.8)

1 (7.7)

240 (94.6)

147 (96.5)

50 (94.1)

248 (92.2)

12 (92.3)

0.18b

Barium exposure

Cat 0

Cat 1

Cat 2

Cat 3

Missing

240 (34.1)

144 (20.5)

51 (7.2)

256 (36.4)

13 (1.8)

13 (5.4)

5 (3.5)

3 (5.9)

20 (7.8)

1 (7.7)

240 (94.6)

147 (96.5)

50 (94.1)

248 (92.2)

12 (92.3)

0.18b

Table 1.Characteristics of screened workforce and unadjusted analysis of predictors of ILO abnormalities

Nuclear Weapons Workers

The 5.6% prevalence rate of parenchymal abnormalities in this study is

higher than the 2.2% rate found in current and former construction and craft

workers from three nuclear weapons sites (Dement et al., 2003 AJIM,

43:559-573) but comparable to a 5.4% rate found in former production

workers from Savannah River Site (Makie et al., 2005, 48:365-372)

The 2.4% prevalence rate of parenchymal/pleural and the 4.6% prevalence

rate of pleural abnormalities found in this study are lower than rates

reported from other nuclear weapons sites: 3.2% and 19.9% respectively in

current and former construction and craft workers from three nuclear

weapons sites (Dement et al., 2003 AJIM, 43:559-573) and 3.7% and

11.3% in former production workers from Savannah River Site (Makie et al.,

2005, 48:365-372) .

None of the modeled exposures were statistically significantly associated

with the increase in risk of parenchymal abnormalities and age was a

strong confounder in all the models (p<0.001)

A suggested dose-response trend was found between exposure to high

explosives/barium and the risk of parenchymal abnormalities. A suggested

dose-response trend was also found between exposure to asbestos and

the risk of parenchymal/pleural abnormalities and pleural abnormalities

alone.

The first hire date on-site was associated with the decrease in risk of

parenchymal abnormalities and pleural abnormalities (p=0.0009 and

p=0.0727 respectively) with those first hired during the Vietnam War era

(1965 to mid-1975) having a statistically significant lower risk of both types

of abnormalities as compared to those hired in the first years (1947-1950)

of nuclear weapons operations on site (OR=0.14 95% CI 0.05-0.40 and

OR= 0.27 95% CI 0.10-0.72 respectively).

This study used multiple ILO readers protocol but found a substantial inter-

reader agreement with regards to both profusion score and pleural

abnormalities.

The results of this study confirm the need to screen former nuclear

weapons workers for pulmonary health effects of airborne exposures in the

manufacture of nuclear weapons

Further epidemiological studies are needed to investigate the suggested

increased risk of parenchymal abnormalities in those exposed directly to

high explosives and barium.

Exposure Beryllium Asbestos High Explosives/Barium

Category 0

No exposure, same as

background:

Administrative, Security, Storage,

Medical, Power Plant, Firing Site,

Auto/Equipment Mechanics,

Cafeteria, Carpenter, Custodian

Not assigned Administrative, Security, Medical,

Power Plant, Cafeteria, Carpenter,

Custodian, Auto/Equipment

Mechanics

Category 1

Rare/low indirect or

bystander

Production and Explosive Operator,

Scientist, Engineer, Pipefitter,

Plumber, Electrician, Laundry,

Administrative, Security, Storage,

Medical, Laundry, Custodian,

Electrician, Firing site, Production

and Explosive Operator, Millwright,

Tool and Die, Machinist,

Production (assembly), Laundry,

Millwright, Tool and Die, Machinist,

Inspector, Storage

Category 2

Occasional, direct or

indirect

Millwright, Tool and Die, Machinist, Power Plant, Auto/Equipment

Mechanics

Pipefitter, Plumber, Process

Engineer, Firing Site

Category 3

Frequent, direct

Not assigned Pipefitter, plumber, carpenter, Production (fabrication) and

Explosive Operator Melt, Scientist,

Agreement Parameter/Reader Reader 1 vs. 2 Reader 1 vs. 3 Reader 2 vs. 3

Profusion Score

Unweighted Kappa Statistic

Weighted Kappa Statistic (FC)

0.31; 95% CI 0.24-0.37

0.68; 95% CI 0.57-0.78

0.36; 95% CI 0.30-0.42

0.72; 95% CI 0.64-0.80

0.52; 95% CI 0.45-0.59

0.70; 95% CI 0.59-0.81

Parenchymal Abnormalities (Y/N)

Unweighted Kappa Statistic 0.57; 95% CI 0.47-0.67 0.67; 95% CI 0.59-0.76 0.56; 95% CI 0.46-0.66

Pleural Abnormalities (Y/N)

Unweighted Kappa Statistic 0.61; 95% CI 0.50-0.72 0.53; 95% CI 0.41-0.64 0.56; 95% CI 0.43-0.69

Exposure Parenchymal (Y/N)1

N=704

n, (%)

ParPleural (Y/N)2

N=680

n,(%)

Pleural (Y/N) 3

N=697

n, (%)

p-value1 p-value2 p-value3

Asbestos

Cat 0

Cat 1

Cat 2

Cat 3

Missing

-

37 (5.8) / 561 (94.2)

3 (7.3) / 35 (92.7)

1 (1.6) / 54 (98.4)

1 (7.7) / 12 (92.3)

-

14 (2.4) / 561 (97.6)

1 (2.8) / 35 (97.2)

3 (5.6) / 54 (94.4)

0 (0.0) / 12 (100.0)

-

27 (4.6) / 561 (95.4)

2 (5.4) / 35 (94.6)

6 (10.0) / 54 (90.0)

0(0.0) / 12 (100.0)

0.29b 0.23b 0.08b

Table 2.Unadjusted analysis of asbestos exposure as a predictor of ILO abnormalities

a Fisher’s exact test; b Cochran-Armitage chi-square Test

Table 3. Analysis of exposure predictors of ILO parenchymal abnormalities adjusted for age, sex, race, and smoking

Exposure OR (95% CI) p-value

Beryllium exposure

Cat 0

Cat 1

Cat 2

1.0

1.37 (0.71-2.64)

0.54 (0.12-2.45)

0.38

High explosives exposure

Cat 0

Cat 1

Cat 2

Cat 3

1.0

0.66 (0.23-1.90)

0.92 (0.25-3.42)

1.49 (0.72-3.04)

0.38

Barium exposure

Cat 0

Cat 1

Cat 2

Cat 3

1.0

0.66 (0.23-1.90)

0.92 (0.29-3.98)

1.49 (0.72-3.09)

0.38

Asbestos exposure (Parenchymal)

Cat 0

Cat 1

Cat 2

Cat 3

-

1.0

0.97 (0.28-3.38)

0.18 (0.02-1.36)

0.25

Asbestos exposure (Parenchymal and Pleural)

Cat 0

Cat 1

Cat 2

Cat 3

-

1.0

0.92 (0.12-7.26)

1.63 (0.44-6.09)

0.76

Asbestos exposure (Pleural)

Cat 0

Cat 1

Cat 2

Cat 3

-

1.0

0.93 (0.21-4.12)

1.59 (0.61-4.16)

0.62

Table 5. Agreement between ILO readers n=757

Parameter OR (95% CI) p-value

First date of hire and parenchymal abnormalities

1/1/1947-12/31/1950

1/1/1951-12/31/1953

1/1/1954-12/31/1964

1/1/1965-6/30/1975

1.0

0.39 (0.16-0.91)

0.53 (0.22-1.29)

0.14 (0.05-0.40)

0.0009

First date of hire and parenchymal + pleural abnormalities

1/1/1947-12/31/1950

1/1/1951-12/31/1953

1/1/1954-12/31/1964

1/1/1965-6/30/1975

1.0

3.75 (0.47-30.16)

2.30 (0.25-20.94)

0.96 (0.11-8.68)

0.1234

First date of hire and pleural abnormalities

1/1/1947-12/31/1950

1/1/1951-12/31/1953

1/1/1954-12/31/1964

1/1/1965-6/30/1975

1.0

0.57 (0.22-1.49)

0.50 (0.18-1.44)

0.27(0.10-0.72)

0.0727

Table 4.Analysis of the first hire date as a predictor of ILO abnormalities adjusted for sex, race, and smoking history